The present invention is directed generally to drift eliminators for removing mist from gas stream. Specifically, the invention is directed to an improved drift eliminator for removing water droplets from a forced airstream in evaporative cooling equipment, for example cooling towers, evaporative condensors, closed circuit fluid coolers, etc.
Drift eliminators, also referred to as mist eliminators, are known. For example, U.S. Pat. No. 3,442,494 illustrates a drift eliminator arranged at the exhaust end of an evaporative heat exchanger to remove water droplets from the exiting air stream. Such prior art drift eliminators are manufactured from either metal or a combination of thermoformed polymeric plastic material and metal. A problem with metal drift eliminators is that the metal corrodes and rusts. The corrosion and rust reduce the life of the eliminator and also deposit on the eliminator blades, significantly reducing the operating efficiency of the eliminator. Other problems with metal drift eliminators are that they are heavy and expensive, and they create a relatively high air pressure drop across the eliminator.
Plastic or PVC drift eliminators overcome many of the problems exhibited by metal drift eliminators. Plastic drift eliminators do not rust or corrode, and are lighter and less expensive than metal eliminators.
A problem with known plastic drift eliminators is that they are manufactured from thick extruded parts and, although lighter than their metal counterparts, are nonetheless relatively heavy and expensive compared to the drift eliminators of the present invention. Moreover, known plastic drift eliminators utilize metal frame members, such as metal rods and fasteners to fasten the blades together and to provide structural integrity. The metal rods and fasteners corrode and rust and therefore these plastic eliminators suffer from many of the same problems as metal drift eliminators. The plastic eliminators also are subject to a relatively high pressure drop.
The present invention provides a plastic drift eliminator preferably made of polymeric plastic which is strong, inexpensive, and light, on the order of about 85% lighter than metal drift eliminators and about 33% to 65% lighter than known prior art plastic drift eliminators. For example, for a typical size eliminator, say one having plan area of 72 inches by 20 inches, the present invention would weigh about 11 pounds, compared with about 87 pounds for a known steel eliminator and about 16 to 31 pounds for known plastic eliminators. The light weight is important for maintenance purposes, shipping, and the like.
The strength to weight ratio of the drift eliminators of the present invention is very good, due to their construction. The drift eliminators of the present invention do not require any metal framing members, such as fasteners or rods. The present invention comprises a high efficiency drift eliminator which has blades having a structure so as to operate with a relatively low pressure drop across the eliminator.